Limit the usage of fully qualified type names in order to prevent name clashing.

Wrong example:

  System.Collections.Generic.List<int> list = new System.Collections.Generic.List<int>();

Correct example:

  using System.Collections.Generic;
  List<int> list = new List<int>();

If you do need to prevent name clashing, use a using directive to assign an alias:

  using WebUILabel = System.Web.UI.WebControls.Label;